Position profile

[nick09]

For my programme, I need to generate a motion to a target position with a target velocity(ie i do not want the motor stop at target position, instead continue with moving in a constant velocity) in a specified time. Would you advise me how to do it and which vi is the best choice?

FYI. I'm using PCI-7342, stepper motor and using labview 7.0.

[mhaag]

Thank you for contacting National Instruments. From your description it sounds like you simply want to make a velocity move where you specify a velocity, acceleration, and deceleration and then your motor will continue to move until you programmatically or manually stop the movement.

If you have not already looked at them, there are a number of shipping examples that are included with NI-Motion. These examples can be found by going to the Help menu in LabVIEW and selecting "Find Examples..." When the NI Example Finder opens, you should choose to browse by directory structure and then navigate to Motion >> FlexMotion. Here you will find a number of examples, with some basic ones under One Axis.llb.

Also, I have included a link below to an example on our w
ebsite that shows how to perform a Constant Velocity Move:

Constant Velocity Move with LabVIEW

With these moves you can still monitor the encoder so that you know when you have reached and passed your target position. If this does not answer your question or if you have any more specific questions then please let us know.

Regards,
Michael
Applications Engineer
National Instruments

[nick09]

Thanks for replying. After understanding the motion created using Constant Velocity Move, I realized that isn't what I want to generate.

Basically, I do not want to generate a profile that accelerate to a constant velocity. In fact, I need to generate a motion where it creates a smooth path from an initial point to the final point I specified in a given time (ie, I will input the initial and final position and velocity.) Besides, the motor shouldn't stop after reaching the target position but continue moving with the final velocity.

Would there be any recommended function that works on this? Will appreciatte if you could attach me some relevants examples.

Thanks and hope to hear from you soon.

[mhaag]

Glad to hear that you are learning more about the system and what can be done. I guess I am still a little unclear as to what exactly needs to be done in your application. I have a few questions that may help us clarify your needs:

• Is your final position and target position the same?
• How will your system eventually stop - will it be based on a position or simply based on a user input?
• What do you mean by a smooth path? (all moves will have some acceleration/deceleration associated with them so no move will have the same velocity from start to finish)

Also, were you able to examine and play around with some of the example programs that ship with LabVIEW? There are a number of simple, one-axis moves that can help y
ou get started with how the VIs work together and how the different parameters (such as velocity, position, acceleration, etc.) affect your move.

Regards,
Michael
Applications Engineer
National Instruments